How to create asp.net Custom web controls event handler

Question

I have a OptionRadioButtonList class extends RadioButtonList web controls:

public class OptionRadioButtonList : RadioButtonList
{
    public EventHandler SelectionChangeEventHandler;
    public OptionRadioButtonList()
    {
        RepeatDirection = RepeatDirection.Vertical;
        AutoPostBack = true;
        Items.Add(new ListItem("YES", "YES"));
        Items.Add(new ListItem("NO", "NO"));
        CssClass = "rbList";
    }
    protected virtual void OnSelectionIndexChanged(object sender, EventArgs e)
    {
        if (SelectionChangeEventHandler != null)
        {
            SelectionChangeEventHandler(sender, e);
        }
    }
}

This class is used in a aspx.cs file like this:

protected void Page_Load(object sender, EventArgs e)
{
    // more code here
    OptionRadioButtonList rblist = new OptionRadioButtonList();
    rblist.SelectionChangeEventHandler += new EventHandler(mainQuestion_rblistHandler);
    LocalPlaceHolder.Controls.Add(rblist);   // this is a placeholder in aspx file
    // more code here
}
// RadioButtonList Event handler
protected void mainQuestion_rblistHandler(object sender, EventArgs e)
{
   RadioButtonList currentRblist = (RadioButtonList)sender;
   if (currentRblist.SelectedValue.Equals("YES"))
   {
      // do something
   } 
   else
   {
      // do something else      
   }
}

So the UI part works fine, but when I change the selection of the yes no radiobuttonList , the Page_Load function gets called, but not mainQuestion_rblistHandler can not be reached when I set a break points there. I am not sure what I did wrong, can anyone help me. Thank you in advance.

Answer 1

You never call OnSelectionIndexChanged . Override the base OnSelectedIndexChanged method and call OnSelectionIndexChanged in there.

public class OptionRadioButtonList : RadioButtonList
{
    public EventHandler SelectionChangeEventHandler;
    public OptionRadioButtonList()
    {

        RepeatDirection = RepeatDirection.Vertical;
        AutoPostBack = true;
        Items.Add(new ListItem("YES", "YES"));
        Items.Add(new ListItem("NO", "NO"));
        CssClass = "rbList";
    }

    protected override void OnSelectedIndexChanged(EventArgs e)
    {
        var handler = SelectionChangeEventHandler;
        if (handler == null) return;
        handler(this, e);
    }
}